All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The name Al-Harith is one of the truest names. The Prophet said: “Call yourselves by the names of the Prophets. The names dearest to Allah are Abdullah and AbdurRahman, the truest are Harith and Hammam, and the worst are Harb and Murrah.
Al-Khattabi mentioned in Ma'alim Al-Sunan the fact in Al-Harith being the truest of the names: “Indeed, Al-Harith is one of the truest names due to the name matching its meaning from which it was derived, and that is because the meaning of “Al-Harith, the earner” is said to be the man’s plow if he earns, and the cultivation of money is his earning.”
Based on the above, the name Harith is a good name, and it does not harm that it agrees with one of the names of Iblees, as Al-Hafidh Ibn Hajar mentioned in Fat'h Al-Bari that among the names of Iblees are Al-Harith and Al-Hakam, and his nickname is Abu Murrah.
Allah knows best.